From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E8027C10DCE for ; Sun, 8 Mar 2020 10:14:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C1926206D7 for ; Sun, 8 Mar 2020 10:14:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726267AbgCHKOo (ORCPT ); Sun, 8 Mar 2020 06:14:44 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:56477 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726180AbgCHKOm (ORCPT ); Sun, 8 Mar 2020 06:14:42 -0400 Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1jAsx5-0004nZ-7p; Sun, 08 Mar 2020 11:14:31 +0100 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id 5F51F1C220A; Sun, 8 Mar 2020 11:14:29 +0100 (CET) Date: Sun, 08 Mar 2020 10:14:29 -0000 From: "tip-bot2 for Thomas Gleixner" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: irq/core] genirq: Provide interrupt injection mechanism Cc: Thomas Gleixner , Kuppuswamy Sathyanarayanan , Marc Zyngier , x86 , LKML In-Reply-To: <20200306130623.990928309@linutronix.de> References: <20200306130623.990928309@linutronix.de> MIME-Version: 1.0 Message-ID: <158366246912.28353.2257142404263650679.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the irq/core branch of tip: Commit-ID: acd26bcf362708594ea081ef55140e37d0854ed2 Gitweb: https://git.kernel.org/tip/acd26bcf362708594ea081ef55140e37d0854ed2 Author: Thomas Gleixner AuthorDate: Fri, 06 Mar 2020 14:03:47 +01:00 Committer: Thomas Gleixner CommitterDate: Sun, 08 Mar 2020 11:06:42 +01:00 genirq: Provide interrupt injection mechanism Error injection mechanisms need a half ways safe way to inject interrupts as invoking generic_handle_irq() or the actual device interrupt handler directly from e.g. a debugfs write is not guaranteed to be safe. On x86 generic_handle_irq() is unsafe due to the hardware trainwreck which is the base of x86 interrupt delivery and affinity management. Move the irq debugfs injection code into a separate function which can be used by error injection code as well. The implementation prevents at least that state is corrupted, but it cannot close a very tiny race window on x86 which might result in a stale and not serviced device interrupt under very unlikely circumstances. This is explicitly for debugging and testing and not for production use or abuse in random driver code. Signed-off-by: Thomas Gleixner Tested-by: Kuppuswamy Sathyanarayanan Reviewed-by: Kuppuswamy Sathyanarayanan Acked-by: Marc Zyngier Link: https://lkml.kernel.org/r/20200306130623.990928309@linutronix.de --- include/linux/interrupt.h | 2 +- kernel/irq/Kconfig | 5 ++++- kernel/irq/chip.c | 2 +- kernel/irq/debugfs.c | 34 +------------------------ kernel/irq/internals.h | 2 +- kernel/irq/resend.c | 53 ++++++++++++++++++++++++++++++++++++-- 6 files changed, 61 insertions(+), 37 deletions(-) diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index c5fe60e..80f637c 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -248,6 +248,8 @@ extern void enable_percpu_nmi(unsigned int irq, unsigned int type); extern int prepare_percpu_nmi(unsigned int irq); extern void teardown_percpu_nmi(unsigned int irq); +extern int irq_inject_interrupt(unsigned int irq); + /* The following three functions are for the core kernel use only. */ extern void suspend_device_irqs(void); extern void resume_device_irqs(void); diff --git a/kernel/irq/Kconfig b/kernel/irq/Kconfig index f92d9a6..20d501a 100644 --- a/kernel/irq/Kconfig +++ b/kernel/irq/Kconfig @@ -43,6 +43,10 @@ config GENERIC_IRQ_MIGRATION config AUTO_IRQ_AFFINITY bool +# Interrupt injection mechanism +config GENERIC_IRQ_INJECTION + bool + # Tasklet based software resend for pending interrupts on enable_irq() config HARDIRQS_SW_RESEND bool @@ -127,6 +131,7 @@ config SPARSE_IRQ config GENERIC_IRQ_DEBUGFS bool "Expose irq internals in debugfs" depends on DEBUG_FS + select GENERIC_IRQ_INJECTION default n ---help--- diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index b3fa2d8..41e7e37 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -278,7 +278,7 @@ int irq_startup(struct irq_desc *desc, bool resend, bool force) } } if (resend) - check_irq_resend(desc); + check_irq_resend(desc, false); return ret; } diff --git a/kernel/irq/debugfs.c b/kernel/irq/debugfs.c index 0c60779..4f9f844 100644 --- a/kernel/irq/debugfs.c +++ b/kernel/irq/debugfs.c @@ -190,39 +190,7 @@ static ssize_t irq_debug_write(struct file *file, const char __user *user_buf, return -EFAULT; if (!strncmp(buf, "trigger", size)) { - unsigned long flags; - int err; - - /* Try the HW interface first */ - err = irq_set_irqchip_state(irq_desc_get_irq(desc), - IRQCHIP_STATE_PENDING, true); - if (!err) - return count; - - /* - * Otherwise, try to inject via the resend interface, - * which may or may not succeed. - */ - chip_bus_lock(desc); - raw_spin_lock_irqsave(&desc->lock, flags); - - /* - * Don't allow injection when the interrupt is: - * - Level or NMI type - * - not activated - * - replaying already - */ - if (irq_settings_is_level(desc) || - !irqd_is_activated(&desc->irq_data) || - (desc->istate & (IRQS_NMI | IRQS_REPLAY))) { - err = -EINVAL; - } else { - desc->istate |= IRQS_PENDING; - err = check_irq_resend(desc); - } - - raw_spin_unlock_irqrestore(&desc->lock, flags); - chip_bus_sync_unlock(desc); + int err = irq_inject_interrupt(irq_desc_get_irq(desc)); return err ? err : count; } diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h index 8980859..7db284b 100644 --- a/kernel/irq/internals.h +++ b/kernel/irq/internals.h @@ -108,7 +108,7 @@ irqreturn_t handle_irq_event_percpu(struct irq_desc *desc); irqreturn_t handle_irq_event(struct irq_desc *desc); /* Resending of interrupts :*/ -int check_irq_resend(struct irq_desc *desc); +int check_irq_resend(struct irq_desc *desc, bool inject); bool irq_wait_for_poll(struct irq_desc *desc); void __irq_wake_thread(struct irq_desc *desc, struct irqaction *action); diff --git a/kernel/irq/resend.c b/kernel/irq/resend.c index bef72dc..27634f4 100644 --- a/kernel/irq/resend.c +++ b/kernel/irq/resend.c @@ -91,7 +91,7 @@ static int irq_sw_resend(struct irq_desc *desc) * * Is called with interrupts disabled and desc->lock held. */ -int check_irq_resend(struct irq_desc *desc) +int check_irq_resend(struct irq_desc *desc, bool inject) { int err = 0; @@ -108,7 +108,7 @@ int check_irq_resend(struct irq_desc *desc) if (desc->istate & IRQS_REPLAY) return -EBUSY; - if (!(desc->istate & IRQS_PENDING)) + if (!(desc->istate & IRQS_PENDING) && !inject) return 0; desc->istate &= ~IRQS_PENDING; @@ -122,3 +122,52 @@ int check_irq_resend(struct irq_desc *desc) desc->istate |= IRQS_REPLAY; return err; } + +#ifdef CONFIG_GENERIC_IRQ_INJECTION +/** + * irq_inject_interrupt - Inject an interrupt for testing/error injection + * @irq: The interrupt number + * + * This function must only be used for debug and testing purposes! + * + * Especially on x86 this can cause a premature completion of an interrupt + * affinity change causing the interrupt line to become stale. Very + * unlikely, but possible. + * + * The injection can fail for various reasons: + * - Interrupt is not activated + * - Interrupt is NMI type or currently replaying + * - Interrupt is level type + * - Interrupt does not support hardware retrigger and software resend is + * either not enabled or not possible for the interrupt. + */ +int irq_inject_interrupt(unsigned int irq) +{ + struct irq_desc *desc; + unsigned long flags; + int err; + + /* Try the state injection hardware interface first */ + if (!irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, true)) + return 0; + + /* That failed, try via the resend mechanism */ + desc = irq_get_desc_buslock(irq, &flags, 0); + if (!desc) + return -EINVAL; + + /* + * Only try to inject when the interrupt is: + * - not NMI type + * - activated + */ + if ((desc->istate & IRQS_NMI) || !irqd_is_activated(&desc->irq_data)) + err = -EINVAL; + else + err = check_irq_resend(desc, true); + + irq_put_desc_busunlock(desc, flags); + return err; +} +EXPORT_SYMBOL_GPL(irq_inject_interrupt); +#endif